[FEATURE] `claude plugin test` and `claude plugin validate` do not type-check TypeScript mods

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

The mod API ships full TypeScript types (.claude-plugin/types/ with a tsconfig.json that sets strict), but neither claude plugin test nor claude plugin validate runs a type check. Tests are executed with types stripped, so a plugin with type errors passes both commands.

What Should Happen?

• claude plugin validate type-checks the plugin with the tsconfig.json it already has, and fails on errors. This would be the natural place, since validate already reads the hooks module and lists the events, $ calls and env variables it uses.
• Or an opt-in flag such as claude plugin test --typecheck.
• Or at least a note in the plugin docs that both commands skip type checking, so authors know to add their own.

Error Messages/Logs

Steps to Reproduce

1. In any TypeScript mod, add a file under hooks/ (or a test) with a type error:

``ts
export const probe: number = 'a'
``

1. Run claude plugin validate <plugin-dir>: it prints ✔ Validation passed.
2. Run claude plugin test <plugin-dir>: every test passes.
3. Run tsc --noEmit -p <plugin-dir>: it reports TS2322: Type 'string' is not assignable to type 'number'.

We also saw this in a real test: a test that passed a malformed SessionUsage mock (context: undefined) ran and passed under claude plugin test, while tsc reported TS2322 for the same line.

Claude Model

None

Is this a regression?

No, this never worked

Last Working Version

_No response_

Claude Code Version

2.1.289

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Windows Terminal

Additional Information

We added a root package.json with typescript (pinned to 7.0.2) as a dev dependency and a script that runs tsc --noEmit -p <plugin-dir> next to claude plugin test and claude plugin validate. This works, but every mod repository has to set it up, and a plugin repo then needs Node and npm tooling even though the mod itself needs neither.

Node v24.20.0 was used.